March 19 (Reuters) - Wall Street's main indexes opened

higher on Wednesday ahead of the Federal Reserve's widely

anticipated monetary policy decision, at a time when worries

about trade policies and their impact on the economy have

rattled investors.

The Dow Jones Industrial Average rose 84.73 points,

or 0.20%, to 41,666.04, the S&P 500 gained 18.29 points,

or 0.33%, to 5,632.95, and the Nasdaq Composite gained

84.20 points, or 0.50%, to 17,588.32 at the opening bell.